Intermediate additively manufactured component

ABSTRACT

An intermediate component with an internal passageway includes a solid metallic additively manufactured component with an internal passageway in a near finished shape. The component has voids greater than 0 percent but less than approximately 15 percent by volume and up to 15 percent additional material by volume in the near finished shape compared to a desired finished configuration. Also included are a ceramic core disposed within the internal passageway of the component and an outer ceramic shell mold encasing an entirety of the component, such that an entire external surface of the component is covered by the outer ceramic shell mold.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. application Ser. No.14/784,857, filed Oct. 15, 2015 entitled “Regenerating An AdditivelyManufactured Component”, which is a §371 National Stage of PCTApplication No. PCT/US2014/34455, entitled “Regenerating An AdditivelyManufactured Component”, filed Apr. 17, 2014, which claims priority toU.S. provisional application Ser. No. 61/813,871, filed on Apr. 19,2013, and entitled “Method For Forming Single Crystal Parts UsingAdditive Manufacturing And Remelt,” the disclosure of which isincorporated by reference herein in its entirety.

BACKGROUND

The present embodiments relate generally to the field of additivemanufacturing and, more particularly, to curing defects in an additivelymanufactured component.

Additive manufacturing is a process by which parts can be made in alayer-by-layer fashion by machines that create each layer according to athree dimensional (3D) computer model of the part. In powder bedadditive manufacturing, a layer of powder is spread on a platform andselective areas are joined by sintering or melting by a directed energybeam. The platform is indexed down, another layer of powder is applied,and selected areas are again joined. The process is repeated until afinished 3D part is produced. In direct deposit additive manufacturingtechnology, small amounts of molten or semi-solid material are appliedto a platform according to a 3D model of a part by extrusion, injection,or wire feed and energized by an energy beam to bond the material toform a part. Common additive manufacturing processes include selectivelaser sintering, direct laser melting, direct metal laser sintering(DMLS), electron beam melting, laser powder deposition, electron beamwire deposition, etc.

Because a part is produced in a continuous process in an additivemanufacturing operation, features associated with conventionalmanufacturing processes such as machining, forging, welding, casting,etc. can be eliminated leading to savings in cost, material, and time.Furthermore, additive manufacturing allows components with complexgeometries to be built relatively easily, compared to conventionalmanufacturing processes.

However, one challenge associated with additive manufacturing is qualitycontrol of the component being additively built. Generally, componentsubsurface defects are inherent in additive manufacturing processes. Itcan take tens of hours (or more) to additively build a component, yet itis inevitable that at least some finished additively built componentswill have subsurface defects, such as contaminates and voids. As aresult, such defective components are rejected after spendingsignificant resources in building these components.

SUMMARY

One embodiment includes a method to regenerate a component. The methodincludes additively manufacturing a component to have voids greater than0 percent but less than approximately 15 percent by volume in a nearfinished shape. The component is encased in a shell mold. The shell moldis cured. The encased component is placed in a furnace and the componentis melted. The component is solidified in the shell mold. The shell moldis removed from the solidified component.

Another embodiment includes a method to regenerate a component withinternal passageways. The method includes additively manufacturing thecomponent to have voids greater than 0 percent but less thanapproximately 15 percent by volume with an internal passageway in a nearfinished shape. The internal passageway is filled with a slurry. Theslurry is cured to form a core. The component is encased in a shellmold. The shell mold is cured. The encased component is placed in afurnace and the component is melted. The component is solidified in theshell mold. The shell mold and core are removed from the solidifiedcomponent.

A further embodiment includes an intermediate component with an internalpassageway. The intermediate component includes a solid metallicadditively manufactured component with an internal passageway in a nearfinished shape. The component has voids greater than 0 percent but lessthan approximately 15 percent by volume and up to 15 percent additionalmaterial by volume in the near finished shape compared to a desiredfinished configuration. Also included are a ceramic core disposed withinthe internal passageway of the component and an outer ceramic shell moldencasing an entirety of the component, such that an entire externalsurface of the component is covered by the outer ceramic shell mold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an intermediate component, withinternal passageways, having a core and a shell mold.

FIG. 2 is a flow chart illustrating a method to regenerate an additivelymanufactured component.

While the above-identified drawing figures set forth one or moreembodiments of the invention, other embodiments are also contemplated.In all cases, this disclosure presents the invention by way ofrepresentation and not limitation. It should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art, which fall within the scope and spirit of the principles of theinvention. The figures may not be drawn to scale, and applications andembodiments of the present invention may include features and componentsnot specifically shown in the drawings.

DETAILED DESCRIPTION

Generally, the present embodiments provide for manufacturing orregenerating an additively manufactured component with defects (e.g.,subsurface defects) to cure the defects such that the component need notbe rejected and can be used as intended. Defects in an additivelymanufactured component are cured by using the component as a pattern tocreate a shell mold, similar to a shell mold for a conventionalinvestment casting process. The component can be completely encased in ashell mold, melted, and then solidified to produce a substantiallydefectless component of the same, potentially complex, shape. Otherfeatures and benefits will be recognized in view of the entirety of thepresent disclosure, including the accompanying figures.

FIG. 1 is a schematic, cross-sectional view of additively manufacturedintermediate component 10. Intermediate component 10 can be a turbineblade which includes airfoil 12, platform 14, root 16, and internalpassageways 18. Intermediate component 10 as shown in FIG. 1 is just oneexample, provided by way of example and not limitation. Additivelymanufactured component 10 can be any component capable of beingadditively manufactured, which can include, for example, a fuel nozzleor turbine blade or vane. Included with intermediate component 10, andshown in FIG. 1, are inner core 20 and outer shell mold 22. In oneexample as shown in FIG. 1, core 20 is a ceramic core and shell mold 22is a ceramic shell mold. Other core 20 and shell mold 22 materials arealso contemplated.

Intermediate component 10 is additively manufactured in a near finishedshape such that airfoil 12, platform 14, root 16, and internalpassageways 18 are integral to component 10. However, ceramic core 20and ceramic shell mold 22 are not formed as part of component 10 duringan additive manufacturing process. Component 10 can be additivelymanufactured using any type of additive manufacturing process whichutilizes layer-by-layer construction, including, but not limited to,selective laser sintering, selective laser melting, direct metaldeposition, direct metal laser sintering (DMLS), direct metal lasermelting, electron beam melting, electron beam wire melting, and othersknown in the art. Component 10 is additively manufactured to have up to15 percent additional material by volume in the near finished shape(i.e., intermediate component 10 as shown in FIG. 1) as compared to adesired finished configuration of component 10 (i.e., component 10 afterbeing regenerated to be substantially free of subsurface defects). Anyadditional material of component 10 can be located at any location whereextra material can be machined. In one example, the extra material canbe located at root 16 and/or a tip of airfoil 12. Moreover, component 10can be additively manufactured to be of a metal, such as a nickel-basedsuperalloy, cobalt-based superalloy, iron-based superalloy, and mixturesthereof.

Component 10, as a result of being additively manufactured, may havesubsurface defects. Subsurface defects can include unwanted defects,such as contaminates and/or voids. Voids can include, for example, poresand/or cracks. For example, component 10 can have voids greater than 0percent but less than approximately 15 percent by volume. Often,component 10 will have voids greater than 0 percent but less thanapproximately 1 percent by volume, and even in some instances less thanapproximately 0.1 percent by volume. Component 10 may be deemedunsuitable for use as intended when containing unwanted levels of voids,which in many applications can be fractions of a single percent byvolume. For this reason, component 10 can be regenerated to curesubsurface defects.

As part of a process for regenerating component 10 to be substantiallyfree of subsurface defects, component 10 has ceramic core 20 and ceramicshell mold 22 added to component 10 after component 10 is additivelymanufactured. In other embodiments, component 10 can have core 20 andshell mold 22 of materials other than ceramic. Ceramic core 20 is formedin internal passageways 18, such that ceramic core 20 substantiallyconforms to a shape of internal passageways 18. Ceramic core 20 can beformed by filling internal passageways 18 with a ceramic slurry,resulting in a volume of internal passageways 18 being occupied by theceramic slurry. The ceramic slurry can be ceramics commonly used as corematerials for investment casting, for example, silica, alumina, zircon,cobalt, mullite, kaolin, and mixtures thereof. Once internal passageways18 are filled, or substantially filled, with the ceramic slurry, theceramic slurry is cured to form ceramic core 20 (having generally solidand rigid properties). In an alternative embodiment, where a componenthas been additively manufactured and does not have an internalpassageway 18, the component can be regenerated to substantially curedefects without the use of ceramic core 20.

Ceramic shell mold 22 is also added to component 10. Ceramic shell mold22 can encase an entirety of component 10, such that an entire externalsurface of component 10 is covered by ceramic shell mold 22 and ceramicshell mold 22 substantially conforms to a shape of component 10.Intermediate component 10 serves as a pattern for making ceramic shellmold 22, because component 10 has a near finished shape. Ceramic shellmold 22 can be formed to encase component 10 by dipping the entirety ofcomponent 10 into a ceramic slurry to form a layer of a green (i.e.uncured) ceramic shell mold on the entirety of component 10. The layeris dried and the component is dipped and dried repeatedly for as manytimes as necessary to form the green ceramic shell mold with anacceptable thickness. A thickness of the green ceramic shell mold canrange from approximately 5 mm to approximately 32 mm. The green ceramicshell mold is then cured to form ceramic shell mold 22 (having generallysolid and rigid properties). The ceramic slurry, and thus ceramic shellmold 22, can be, for example, silica, alumina, zircon, cobalt, mullite,kaolin, and mixtures thereof. Alternatively, in one example, ceramicshell mold 22 and ceramic core 20 can be formed simultaneously such thatceramic shell mold 22 encases the entire external surface of component10 and ceramic core 20 encases an entire surface of internal passageways18.

FIG. 2 is a flow chart illustrating an embodiment of additivelymanufactured component regeneration method 30. Method 30 can be used tocure component 10 of subsurface defects such that component 10 can beused as desired and need not be rejected.

First, intermediate component 10, which can optionally include internalpassageway 18, is additively manufactured in a near finished shape (step32). Any type of additive manufacturing process including, but notlimited to, selective laser sintering, selective laser melting, directmetal deposition, direct metal laser sintering, direct metal lasermelting, electron beam melting, electron beam wire melting, and othersknown in the art can be used to additively manufacture component 10.Moreover, component 10 can be additively manufactured to be of a metal,such as a nickel-based superalloy, cobalt-based superalloy, iron-basedsuperalloy, and mixtures thereof. Additively manufactured component 10has unwanted defects, which can include voids (e.g., pores and/orcracks) greater than 0 percent but less than approximately 15 percent byvolume (other unwanted defects can include contamination). In oneembodiment, component 10 has unwanted voids greater than 0 percent butless than approximately 1 percent by volume, and even less thanapproximately 0.1 percent by volume. Furthermore, component 10 can beadditively manufactured to have up to 15 percent additional material byvolume in the near finished shape compared to a desired finishedconfiguration. This means that component 10 as additively built caninclude extra material beyond what is needed to form the desiredfinished configuration. This extra material can be located on component10 at any location where extra material may be machined. In one example,the extra material can be located at root 16 and/or the tip of airfoil12 such as at a discrete sprue location. In one embodiment, component 10is intentionally additively manufactured to contain a hollow portion(e.g., a hollow portion resembling a pore of a desired size, shape,etc.) such that the additive manufacturing process is less timeconsuming.

Next, at least one internal passageway 18, if present, can be filledwith a ceramic slurry or other suitable core material (step 34). Fillinginternal passageway 18 with the slurry results in a volume of internalpassageway 18 being occupied by the slurry. Each internal passageway 18can be filled with the slurry. The slurry can be of ceramic materialscommonly used as core materials in conventional casting processes,including, but not limited to, silica, alumina, zircon, cobalt, mullite,and kaolin.

Once internal passageways 18 are filled with the ceramic slurry, theceramic slurry is cured to form inner core 20 (step 36). The slurry canbe cured in situ in component 10 by a suitable thermal process. Core 20occupies internal passageways 18, such that core 20 substantiallyconforms to a shape of internal passageways 18 of component 10. Steps 34and 36 can be omitted if no internal passageway 18 is present.

Then, component 10 is encased in a green (i.e. uncured) shell mold (step38). The green shell mold can encase an entirety of component 10 (i.e.substantially seals component 10), such that an entire external surfaceof component 10 is covered by the green shell mold and the green shellmold substantially conforms to a shape of component 10. There can beinstances where core 20 is at or near the external surface of component10 and core 20 then forms a portion of shell mold 22, resulting in gapsin shell mold 22 over portions of core 20. The green shell mold can beformed to encase component 10 by dipping the entirety of component 10into a ceramic slurry to form a layer of the green ceramic shell mold onthe entirety of component 10. The layer is dried and the component isdipped and dried repeatedly for as many times as necessary to form thegreen shell mold with an acceptable thickness. As one alternative todipping component 10 into the ceramic slurry, the ceramic slurry can bepoured onto component 10 and dried. An acceptable thickness of the greenshell mold can range from approximately 5 mm to approximately 32 mm. Thegreen shell mold can be heated at an intermediate temperature topartially sinter the ceramic and burn off any binder material in thegreen shell mold.

The green shell mold is then cured to form outer shell mold 22 (step40). The shell mold 22, can be, for example, silica, alumina, zircon,cobalt, mullite, kaolin, and mixtures thereof. Ceramic shell mold 22 canbe cured at a temperature ranging between approximately 649° C. (1200°F.) to approximately 982° C. (1800° F.) for a time ranging betweenapproximately 10 to approximately 120 minutes to cure ceramic shell mold22 to full density. Because the green ceramic shell mold encased anentirety of component 10 and substantially conforms to a shape ofcomponent 10, component 10 serves as a pattern in ceramic shell mold 22(in lieu of a wax pattern used in traditional investment castingprocesses).

Next, component 10 with unwanted defects is melted in ceramic shell mold22, which now has the pattern of component 10 (step 42). One way ofmelting component 10 in ceramic shell mold 22 is to place at least partof component 10 in a furnace. However, other means of applying heat suchthat component 10 is melted in ceramic shell mold 22 can be used. Forexample, a dual chill block and furnace assembly can be used. Thematerial from which component 10 is made generally has a melting pointlower than a melting point of the material from which core 20 and shellmold 22 are formed. This can allow component 10 to melt inside ceramicshell mold 20 without contaminating component 10 material with ceramiccore 20 and/or ceramic shell mold 22 material. Melting component 10 inceramic shell mold 22 allows component 10 material to densify, withassistance of gravity or other means, and substantially eliminate theunwanted voids originally present in component 10. If component 10 wasadditively manufactured to have up to 15 percent additional material byvolume, this additional material also melts and fills into pores and/orcracks in component 10 (such that the additional material that fillsinto pores and/or cracks in component 10 is no longer present whereoriginally located). Melting component 10 in shell mold 22 can also helpto rid component 10 of contaminates, which are generally more soluble incomponent 10 liquid phase than component 10 solid phase.

After component 10 has melted inside ceramic shell mold 22, component 10is solidified in ceramic shell mold 22 (step 44). Component 10 can besolidified using a chill block, or any other means of cooling component10 to a temperature at which component 10 can solidify. Solidifyingcomponent 10 in ceramic shell mold 22 forms component 10 to be of thesame shape that component 10 was originally additively manufactured as,but now component 10 has densified and reduced or even substantiallyeliminated voids or other defects (i.e. to a desired finishedconfiguration). If component 10 is directionally solidified using astarter seed or grain selector, contaminates in component 10 will bepushed, or collected, by the solidification interface into a common areaof component 10 which can then be removed and scrapped.

Finally, ceramic core 20 and ceramic shell mold 22 are removed fromsolidified component 10 (step 46). For example, ceramic core 20 can beetched out or removed by caustic leaching and ceramic shell mold 22 canbe knocked out. Finished component 10 can also be inspected to ensureunwanted defects, such as voids, have been reduced or substantiallyeliminated and finished component 10 has the same shape as additivelymanufactured component 10. Method 30 can then be repeated if needed.

Where a component has been additively manufactured and does not have aninternal passageway 18, the component can be regenerated tosubstantially cure subsurface defects similar to that described formethod 30. However, because there is no internal passageway 18, steps 34and 36 need not be performed.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments ofthe present invention.

A method to regenerate a component, the method comprising additivelymanufacturing a component to have voids greater than 0 percent but lessthan approximately 15 percent by volume in a near finished shape;encasing the component in a shell mold; curing the shell mold; placingthe encased component in a furnace and melting the component;solidifying the component in the shell mold; and removing the shell moldfrom the solidified component.

The method of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingtechniques, steps, features, and/or configurations:

The component is additively manufactured to have voids greater than 0percent but less than approximately 1 percent by volume.

The component is additively manufactured to have up to 15 percentadditional material by volume in the near finished shape compared to adesired finished configuration.

The component is a blade or vane and the up to 15 percent additionalmaterial by volume is located at a root or a tip of an airfoil of thecomponent.

Encasing the component in a shell mold comprises encasing an entirety ofthe component in the shell mold such that an entire external surface ofthe component is covered by the shell mold.

Encasing the component in the shell mold comprises a process of: (a)dipping the entirety of the component in a slurry to form a layer of theshell mold on the entirety of the component; (b) drying the layer of theshell mold; and (c) repeating steps (a) and (b) until an acceptableshell mold thickness is formed to encase the entirety of the component.

The component is additively manufactured using at least one of selectivelaser sintering, selective laser melting, direct metal deposition,direct metal laser sintering, direct metal laser melting, and electronbeam melting.

The component is additively manufactured to be of a metal selected fromthe group consisting of a nickel-based superalloy, cobalt-basedsuperalloy, iron-based superalloy, and mixtures thereof.

A method to regenerate a component with internal passageways, the methodcomprising: additively manufacturing the component to have voids greaterthan 0 percent but less than approximately 15 percent by volume with aninternal passageway in a near finished shape; filling the internalpassageway with a slurry; curing the slurry to form a core; encasing thecomponent in a shell mold; curing the shell mold; placing the encasedcomponent in a furnace and melting the component; solidifying thecomponent in the shell mold; and removing the shell mold and core fromthe solidified component.

The method of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingtechniques, steps, features, and/or configurations:

The core substantially conforms to a shape of the internal passageway ofthe component, and shell mold substantially conforms to a shape of thecomponent.

The component is additively manufactured to have voids greater than 0percent but less than approximately 1 percent by volume.

The component is additively manufactured to have up to 15 percentadditional material by volume in the near finished shape compared to adesired finished configuration.

The component is a blade or vane and the up to 15 percent additionalmaterial by volume is located at a root or a tip of an airfoil of thecomponent.

The component is additively manufactured using at least one of selectivelaser sintering, selective laser melting, direct metal deposition,direct metal laser sintering, direct metal laser melting, and electronbeam melting.

The component is additively manufactured to be of a metal selected fromthe group consisting of a nickel based superalloy, cobalt basedsuperalloy, iron based superalloy, and mixtures thereof.

The slurry is selected from the group consisting of silica, alumina,zircon, cobalt, mullite, and kaolin.

The shell mold is selected from the group consisting of silica, alumina,zircon, cobalt, mullite, kaolin, and mixtures thereof.

Encasing the component in a shell mold comprises encasing an entirety ofthe component in the shell mold such that an entire external surface ofthe component is covered by the shell mold.

Encasing the component in the shell mold comprises a process of: (a)dipping the entirety of the component in a slurry to form a layer of theshell mold on the entirety of the component; (b) drying the layer of theshell mold; and (c) repeating steps (a) and (b) until an acceptableshell mold thickness is formed to encase the entirety of the component.

An intermediate component with an internal passageway, the intermediatecomponent comprising: a solid metallic additively manufactured componentwith an internal passageway in a near finished shape, wherein thecomponent has voids greater than 0 percent but less than approximately15 percent by volume and up to 15 percent additional material by volumein the near finished shape compared to a desired finished configuration;a ceramic core disposed within the internal passageway of the component;and an outer ceramic shell mold encasing an entirety of the component,such that an entire external surface of the component is covered by theouter ceramic shell mold.

Any relative terms or terms of degree used herein, such as “generally”,“substantially”, “approximately”, and the like, should be interpreted inaccordance with and subject to any applicable definitions or limitsexpressly stated herein. In all instances, any relative terms or termsof degree used herein should be interpreted to broadly encompass anyrelevant disclosed embodiments as well as such ranges or variations aswould be understood by a person of ordinary skill in the art in view ofthe entirety of the present disclosure, such as to encompass ordinarymanufacturing tolerance variations, incidental alignment variations,temporary alignment or shape variations induced by operationalconditions, and the like.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

The invention claimed is:
 1. An intermediate component with an internalpassageway, the intermediate component comprising: a solid metallicadditively manufactured component with an internal passageway in a nearfinished shape, wherein the component has voids greater than 0 percentbut less than approximately 15 percent by volume and up to 15 percentadditional material by volume in the near finished shape compared to adesired finished configuration; a ceramic core disposed within theinternal passageway of the component; and an outer ceramic shell moldencasing an entirety of the component, such that an entire externalsurface of the component is covered by the outer ceramic shell mold. 2.The intermediate component of claim 1, wherein the component has voidsgreater than 0 percent but less than approximately 1 percent by volume.3. The intermediate component of claim 1, wherein the component hasvoids greater than 0 percent but less than approximately 0.1 percent byvolume.
 4. The intermediate component of claim 1, wherein the componentis a fuel nozzle.
 5. The intermediate component of claim 1, wherein thecomponent is selected from a group consisting of a turbine blade and aturbine vane.
 6. The intermediate component of claim 5, wherein thecomponent comprises: an airfoil; and a root adjacent the airfoil.
 7. Theintermediate component of claim 6, wherein the component furthercomprises: a platform adjacent the root and the airfoil.
 8. Theintermediate component of claim 7, wherein the airfoil, root, andplatform are integrally formed.
 9. The intermediate component of claim6, wherein the additional material by volume is located at the root. 10.The intermediate component of claim 6, wherein the additional materialby volume is located at a tip of the airfoil.
 11. The intermediatecomponent of claim 1, wherein the additional material by volume islocated at a position on the component where the additional material canbe machined.
 12. The intermediate component of claim 1, wherein theceramic core substantially conforms to a shape of the internalpassageway.
 13. The intermediate component of claim 1, wherein thecomponent is a metal selected from the group consisting of anickel-based superalloy, a cobalt-based superalloy, an iron-basedsuperalloy, and mixtures thereof.
 14. The intermediate component ofclaim 1, wherein the ceramic core is a material selected from the groupconsisting of silica, alumina, zircon, cobalt, mullite, and kaolin. 15.The intermediate component of claim 1, wherein the ceramic shell mold isa material selected from the group consisting of silica, alumina,zircon, cobalt, mullite, kaolin, and mixtures thereof.
 16. Theintermediate component of claim 1, wherein the ceramic shell mold has athickness ranging from approximately 5 millimeters to approximately 32millimeters.
 17. The intermediate component of claim 1, wherein thevoids comprise a subsurface defect.
 18. The intermediate component ofclaim 17, wherein the subsurface defect is selected from a groupconsisting of pores and cracks.
 19. The intermediate component of claim1, wherein the component comprises a plurality of internal passageways.